Method and device for separating ethylene from refinery plant dry gas

Abstract

The invention belongs to the field of chemical engineering, and particularly discloses a method and a device for separating ethylene from refinery plant dry gas. The method comprises the steps of compression, purification, cooling, absorption, propane removal, methane removal, and ethylene refining. The method is based on a shallow cold oil absorption technology, directly produces a polymer-gradeethylene product from refinery plant dry gas on the premise that the refrigeration process is simplified, the cold consumption is reduced and the investment is saved, and has great industrial application prospects.

Description

technical field [0001] The invention belongs to the field of chemical industry, and more specifically relates to a method and a device for separating ethylene from refinery dry gas. Background technique [0002] Refinery dry gas is an important resource of petrochemical industry, mainly from primary and secondary processing of crude oil, such as atmospheric and vacuum distillation, catalytic cracking (FCC), catalytic cracking (DCC), hydrocracking, delayed coking, etc., among which The amount of dry gas from catalytic cracking is the largest, generally accounting for 3%-5% of crude oil processing volume, which contains a large amount of light hydrocarbon resources such as hydrogen, methane, ethane, ethylene, propane, and propylene. At present, the annual processing capacity of domestic catalytic cracking units exceeds 200Mt, and the annual output of catalytic dry gas is above 6.0Mt, which contains 0.6-1.0Mt of ethylene. Most of the refinery dry gas is burnt as industrial and...

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Problems solved by technology

However, the ethylene concentration in the product obtained by this method is low, and it still needs to be sent to the ethylene plant for further purification. At the same time, the required operation of the reabsorption tower requires the introduction of a large amount of gasoline absorbent

[0009] To sum up, the ethylene separation process commonly used in industry requires cryogenic conditions, and the refrigeration and heat exchange processes are complicated and not suitable for direct treatment of refinery dry gas, while Oil absorption process for recovering refinery dry gas is mainly to obtain carbon dioxide enriched gas with low ethylene content from refinery dry gas as raw material for ethylene cracking, which is generally not suitable for refineries without supporting ethylene equipment. At the same time, oil absorption process It is also necessary to set up a reabsorption tower or a cold box-expander to reduce the loss of absorbent, and the process is more complicated

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